Strain distributions in carbon-doped silicon nanowires along [110] and [100] investigated by X-ray diffraction

Abstract

Carbon-doped silicon films formed on Si substrates have large tensile strain, and the strain is relaxed by microfabrication into nanowires. We investigated the effects of crystalline orientation, width, and carbon concentration on lattice relaxations by reciprocal space mapping of x-ray diffraction. Reciprocal space mapping profiles of periodically aligned 400-480 carbon-doped silicon nanowires on silicon substrates indicate that lattice relaxation of Si0.9917C0.0083 nanowires along [100] was larger than that of [110] nanowires. The effect of crystalline orientation of nanowires is considered to increase as lattice mismatch to substrate increases, since no difference was observed in residual strains between [100] and [110] nanowires of Si0.9940C0.0060 with smaller lattice mismatch to Si substrate. It has also been revealed that the strains of carbon-doped silicon nanowires were more relaxed as nanowire width decreased